Sebum is skin oil which is produced by sebocytes (cells of the sebaceous glands in the skin) and is then secreted to the skin surface. Excessive amount of sebum on the skin surface results in the condition known as "oily skin." Oily skin is associated with a shiny, undesirable appearance and a disagreeable tactile sensation. Many methods and compositions exist which attempt to control the excessive sebum secretion, but none have proved totally satisfactory.
Formation of free radicals in the skin does not appear to be related to the sebum secretion. Low levels of free radicals are formed in the skin as part of the natural metabolic pathways. The level of free radicals is increased in response to UV radiation and other environmental oxidants, e.g. pollution and cigarette smoke. Increased concentration of free radicals leads to lipid peroxidation in skin cells and cellular damage, which in turn results in a premature ageing of the skin with an accompanying loss of firmness and elasticity, wrinkles, discoloration, age spots, and dryness. Antioxidants, such as vitamin E (alpha-tocopherol), decrease the level of free radicals in the skin.
Cosmetic actives which provide more than one benefit are highly desirable, both from the manufacturer's and consumer's perspective.
Guggal is obtained from a gum/resin of the plant Commiphora mukul or Commiphora wightii. Guggal contains a complex mixture of terpenes, sterols, esters and higher alcohols. The ethyl acetate extract of the resin is an oily resinous material known as "gugulipid" or "guggal lipid." Gugulipid has been used medicinally in the treatment of obesity and elevated cholesterol levels. The medicinal activity of gugulipid is attributed to two known ketonic steroids (guggulsterones).
Bombardelli et al. (U.S. Pat. No. 5,273,747) discloses the anti-inflammatory activity of gugulipid and a guggulsterone-enriched fraction thereof and their use in the treatment of benign prostatic hypertrophy and in the treatment of acne. In this regard it is important to note that although increased sebum production may be one of the many factors that lead to the formation of acne, an anti-acne agent does not necessarily possess antisebum activity. For instance, benzoyl peroxide and salicylic acid are well-established anti-acne agents, but they do not decrease sebum output. See Cunliffe, et al., "Topical Benzoyl Peroxide Increases The Sebum Excretion Rate In Patients With Acne", British Journal of Dermatology (1983) 109, 577-579; William J. Cunliffe, "Acne", p. 256, Martin Dunitz Ltd. (1989). See also Comparative Example 3 below. Furthermore, the guggulsterone-enriched fraction described by Bombardelli was obtained with ethyl acetate and did not separate compounds by molecular weight. By contrast, in the present invention a low molecular weight fraction is employed.
Bissett et al. (U.S. Pat. Nos. 4,847,071 and 4,847,069) and Piazza et al. (U.S. Pat. No. 5,521,223) disclose photoprotective and anti-wrinkle compositions containing guggal as a natural anti-inflammatory. Although some compounds may be anti-inflammatory through antioxidant pathways, not all anti-inflammatory mechanisms are antioxidant mediated, nor are all antioxidant antiinflammatory. Put another way, antiinflammatory and antioxidant effects do not necessarily follow each other.
McCook et al., U.S. Pat. No. 5,690,948, discloses cosmetic antisebum and antioxidant compositions containing gugulipid or an alcoholic fraction thereof. McCook et al. do not teach the use of a low molecular weight fraction. Since gugulipid is dark-brown color and has a tar-like consistency at room temperature, it is difficult to work with and it is difficult to manufacture commercially attractive compositions with gugulipid. The alcoholic fraction has the same shortcomings as gugulipid and, in addition, its yield is relatively low.
It has been found, as part of the present invention, that a low molecular weight fraction of gugulipid is easier to formulate, due to its lower viscosity and better color than any one of: gugulipid, the alcoholic fraction or a high molecular weight fraction. The low molecular weight fraction can also be obtained in a higher yield than the alcoholic fraction. In chemical art, lower molecular weight does not necessarily correlate with lighter color or lower viscosity, especially when naturally occurring plant-derived compounds are surveyed. For instance, naringenin has the molecular weight of 272.2, yet it is brown, whereas glycyrrhizic acid has the molecular weight of 822.92, yet it is colorless. Likewise, tristearin (molecular weight 891.5) is a solid, whereas triolein (approximately the same molecular weight: 885.4) is a liquid.
The art discussed above does not address the need for an agent which contains both antisebum and antioxidant activities and yet is attractive in color and other physical properties and can also be obtained in high yield. Furthermore, as far as fractions of gugulipid are concerned, the above art discloses fractionation based on polarity (ethyl acetate fraction of Bombardelli or alcoholic fraction of McCook), not based on molecular weight. The use, activities and advantages of a low molecular weight fraction are not disclosed or suggested.